Controlled Synthesis of Bi₂O₂Te Nanosheets for High-Performance Broadband Photodetectors

Broadband photodetectors, covering visible to infrared spectra, are widely used in communications, imaging, military, and the medical fields. Recently, low-dimensional material-based photodetectors have gained significant attention. Low-dimensional Bi 2 O 2 Se has been extensively studied for its excellent air stability and optical properties. Similarly, Bi 2 O 2 Te shares these advantages and has a narrower band gap of 0.13 eV. However, research on Bi 2 O 2 Te remains limited, likely due to its challenging synthesis conditions, which have impeded the study of its optoelectronic properties. In this study, we successfully synthesized large-scale (235 μm, the largest reported to date) Bi 2 O 2 Te nanosheets using an upside-down growth chemical vapor deposition method. Furthermore, the fabricated Bi 2 O 2 Te photodetector exhibits broadband photoresponse (520 nm-2 μm), an ultrahigh responsivity of 3679 A W –1, an impressive detectivity of 8.91 × 10 11 cm Hz 1/2 W –1, and a fast response time (τ rise /τ decay ≈ 32/92 μs), demonstrating its potential for applications in high-performance photodetectors. More importantly, this work provides a significant contribution to the further investigation of Bi 2 O 2 Te.